This invention relates to a method for heat-treating amorphous alloys, and more particularly, to a method for heat-treating amorphous alloys having high permeability.
Recently, production techniques for obtaining amorphous alloy foils or ribbons, in which certain component materials are quenched from the molten state to the solid state at extremely high rates, have been developed, and considerable academic and industrial efforts are being undertaken not only to develop their useful applications, but also to further investigate their relevant characteristics. Since the amorphous alloy materials obtained through the splat cooling method are generally free from crystalline anisotropy, the consequent materials are assumed to be potentially useful soft magnetic materials. However, the magnetic properties of the amorphous alloy materials which have been subjected to the splat cooling method are not so preferable, and thus, the heat treatment thereof is conventionally indispensable to improve their inherent properties. With respect to the annealing method for the amorphous alloy material, it has already been well known that the heat treatment is executed at a specific temperature (T.sub.A), when the crystallization temperature (Tx) of the amorphous alloy material is higher than its Curie temperature (Tc). Namely, according to the conventional annealing methods, such temperature (T.sub.A) as described above lies in the range of Tc&lt;T.sub.A &lt;Tx. Hence, such amorphous alloy material having magnetic properties predetermined in advance can be obtained by rapidly cooling the component material to room temperature, after the component material has been heat-treated for a predetermined period at the temperature T.sub.A.
Another undesirable characteristic is that, since these amorphous alloy materials in general exist in a metastable state, irrespective of the fact that they have been annealed through the conventional method, these materials suffer such magnetic aftereffects as the so-called disaccommodation (D.A.) of the consequent material. These deficiencies have been big barriers for useful application of these materials.